Pedicle screw fixation is an increasingly important technique in spine surgery. Pedicle screws are inserted into the vertebrae or spinal column of a patient in order to make it possible for a spinal column of a patient suffering from a traumatic or degenerative disease to perform its proper function. Accurate placement of pedicle screws is vital to avoid iatrogenic injuries to nervous or vascular structures. Accurate placement of the screws in the vertebral body also yields greater bony purchase, therefore increasing pull out strength. Currently, there are a number of methods used to insert pedicle screws into the spine of a patient.
One method of inserting pedicle screws involves blind placement of the screws by a physician. The physician, guided only by sight, drills the holes based on the physician's experience and knowledge of the spine. Such a technique can be effectively practiced only by highly skilled and experienced practitioners and is generally considered a wholly inadequate and not recommended procedure.
Intra-operative navigations systems such as, for example, the Medtronic StealthStation® and Stryker® Navigation Systems, are also used for placement of pedicle screws. These systems provide markers and other structures to guide the physician's drilling process. However, such systems are expensive, add significant time to the surgical procedure due to setup, and can suffer from intra-operative shifting of structures and registration error.
Another technique for placement of pedicle screws utilizes traditional fluoroscopic x-ray techniques. This involves the use of standard x-ray systems, such as C-arms, to image the target pedicle area as the physician drills. Such systems are economical and provide real time data which eliminates intra-operative shift of structures and registration errors. However, they are typically limited to use with anterior-posterior and lateral projections. These systems are also suboptimal when the pedicle sits at angles that are not orthogonal to the base of the X-ray system. In addition, C-arm x-ray systems are large and cumbersome, so repositioning for a procedure can be a lengthy process.
It would be desirable to provide an X-ray directed pedicle screw drill system designed to replace existing methods for drilling pedicle screws with a faster and more accurate system that exposes the patient to a minimal amount of X-ray radiation